Document WO-A2-98/13838 describes an electric module intended to be submerged underwater, of the type comprising:
a sealed enclosure intended to be submerged underwater and containing an atmosphere comprising a heat transfer fluid, referred to as the secondary fluid, for example air or nitrogen;
at least one item of electrical equipment arranged in the sealed enclosure and which, in operation, heats the atmosphere,
a first cooling circuit, referred to as the secondary circuit, for cooling the item or items of electrical equipment, using the secondary fluid, the secondary circuit comprising:
a guiding channel provided with two openings, one, referred to as the bottom opening, being arranged beneath the other, referred to as the top opening, in a position of use of the electric module, the guiding channel being arranged in the sealed enclosure so as to guide the atmosphere which has been heated by the item or items of electrical equipment towards its top opening;
a passage for the atmosphere, the passage linking the top opening to the bottom opening via the outside of the guiding channel and being delimited, at least partly, by the sealed enclosure in order to provide a cooling of the atmosphere upon contact with the sealed enclosure;
In this document, the guiding channel is fixed to the sealed enclosure by a multitude of thermally conductive fins distributed along the circumference of the sealed enclosure.
Moreover, for obvious reasons of operation, it is desirable for the environment of the item or items of electrical equipment to be as dry as possible.
To this end, there exist, first of all, active dehumidifying systems. However, these systems are not reliable enough for undersea use, in particular at depths of greater than 500 meters, at which any repair operation is very difficult.
Passive systems also exist, such as silica gel beads. However, they are not effective enough.